Microelectronic devices such as state-of-the-art microprocessors require large numbers of reliable connections in increasingly-small areas. As the number of connections between an electronic device and a substrate to which the device is to be mounted increases, the likelihood that just a single connection will not be made or will fail, also increases.
In “wave soldering,” an electronic component is soldered to a substrate by flowing molten solder over a substrate in which electronic components are mounted. Components are placed onto the substrate, which is then passed over flowing, molten solder such that exposed metal and fluxed surfaces on the lower surface of the substrate surface wick the molten solder upward from the solder bath. As the substrate with the wicked, molten solder moves away from the molten solder bath, the solder cools and solidifies, establishing an electrical connection between electronic devices and soldered surfaces of the substrate.
As connection density increases in the electronic arts and lead lengths from electronic devices decreases, the increasing number of connections that must be made make it statistically more likely that even a single connection will not be made or will fail. Even minor irregularities in the planarity of a substrate can cause connection problems.
One problem with prior art soldering techniques arises when the contact surfaces of a substrate and an electronic device are separated from each other by different distances. For example, if one or two contact leads or one or two contact surfaces of a microprocessor are more widely separated from a planar substrate than the other contact leads or contact surfaces, the molten solder might not wick between the substrate and the more-distant contact surfaces of the electronic device. Prior art soldering techniques suffer from an inability to make a connection when the spacing or distance between contact surfaces of two devices or surfaces to be joined, varies by more than a small amount.
When even a single connection between an electronic device and its supporting substrate is either not made at the time of manufacture, or if even a single connection fails while the electronic device is in use, the cost to identify a failed electrical connection and to repair it can often exceed the cost to manufacture the product in which the electronic device and supporting substrate operates. Improving the manufacturability of electrical connections and improving the reliability of electrical connections after manufacture would be an improvement over the prior art.
Applicants hereby incorporate by reference herein, the entire disclosure of their co-pending U.S. patent application Ser. No. 11/140,195, filed on May 27, 2005, and entitled “Electro-Formed Ring Interconnection System”, which discloses pliable conductive hollow rings that accommodate circuit flexing, as well as impacts and vibration. While the pliable rings of the co-pending application provide an improved connection, in some instances, the pliable rings may not be able to make a good electrical connection to a surface, especially, if the surface is not clean. As is well-known by those or ordinary skill in the electronic arts, even very thin layers of material that may accumulate on a circuit board trace or contact pad can impede the establishment of a good connection. If there are contaminants or dirt or a film present on a conductive surface, even a contact spring in the form of a ring may not be able to provide a good electrical connection to the traces or contact pads. Surface oxidation, residual conformal coating materials, solder fluxes, atmospheric pollutants and other chemicals can form thin coatings on a metal contact pad that can impede the formation of a solid electrical contact.
In order to avoid these shortcomings, it is desirable to provide a connector with that performs a wiping action across the contact pads or circuit board traces to remove contaminants and/or oxidation and films from the contact surface when the connector is brought into contact with the circuit board. The present invention is directed to an improved ring connector that overcomes the above-mentioned shortcomings.